The field of the disclosure relates generally to electronically commutated motors, and more particularly, to methods and apparatus for average current and input power monitoring in an electronically commutated motors.
Electronically commutated motors (ECMs) are used in a wide variety of applications. ECMs are sometimes referred to in the industry, and herein, as brushless DC motors. One application in which ECMs are deployed is an air flow delivery system. In an airflow delivery system, such as in an evaporator fan unit in a walk-in cooler, it is desirable to know how much power is being used under certain loading conditions to minimize energy usage. This power utilization information can be used to determine when a defrosting cycle is unnecessary or when the system is being under utilized, in order to conserve energy.
Some systems incorporate peak current control circuitry, along with a constant torque algorithm, to determine loading on the motor. The disadvantage to this configuration is that an efficiency estimate must be made in order to calculate the total power input. Generally, this configuration utilizes a lookup table for obtaining the efficiency estimate. Better data can be obtained if a real time power measurement is utilized instead of a lookup table.